The present invention relates to a structure of a wrist having three degrees of freedom for use with an industrial robot.
A wrist coupled to the end of the arm of an industrial robot is required to have suitable motions for carrying out a desired job in three dimensional space. Thus, as shown in FIG. 1, an entire wrist B coupled to an arm A must be rotated in a direction shown by an arrow a, the angle of a tool C mounted on the wrist must be adjusted or tilted as shown by a reference character b, and the tool itself must be rotated as shown by a reference character c. In order to meet the above requirements, three drive shafts must be inserted into the interior of the arm supporting the wrist, so that the outer dimension and weight of the arm disadvantageously increase and the power for driving the arm increases as well.